abstract:Plomestane (INN, USAN; MDL-18,962), also referred to as propargylestrenedione (PED), is a steroidal, irreversible aromatase inhibitor which was under development by Marion Merrell Dow/Hoechst Marion Russell (now Hoechst AG) as an antineoplastic agent for the treatment of breast cancer. It was found to be effective in preclinical studies and was also found to produce few adverse effects in human clinical trials, significantly reducing estrogen levels with a single administration.